Blogs

AIX Down Under

About this blog

Anthony English is an independent contractor who solves expensive problems for businesses running IBM Power Systems.
He has written extensively about AIX and has been recognised for his contributions and thought leadership by being named an IBM Champion for Power Systems.

Tags

Find us on Facebook

Often in SMIT you can use the default settings, but when it comes to creating Enhanced Journalled File Systems – better known as JFS2 – there are three options which you’ll probably want to change from the defaults. Of course you need to set the MOUNT POINT, but the other three I like to change are: Mount AUTOMATICALLY at system restart? yes (and why wouldn’t you?) Logical volume for Log: INLINE Allow internal snapshots? yes SMIT aside: Tab Toggles In SMIT, when you have a choice between two options, such as yes and no , you can hit the Tab key... [More]

YOUR TIME IS PRECIOUS! When you need to increase a file system, you can use our old friend smitty. But stepping through the SMIT menus could take a good 3 seconds (at least!) And as a good AIX guru, your time is precious. In a perfect world AIX gurus like you should charge your time by the nanosecond! (Just go tell your boss that the bloke who writes AIX Down Under said so.) Alas, the world is not perfect, as you may have discovered after that friendly chat with the boss. Even so, you can save a few seconds when you have to increase a file... [More]

If you are using virtual SCSI (VSCSI) disks, you may occasionally find you need to reclaim them. (Shocking as it may seem, sometimes people actually do give back disk they have requested for some temporary project). Here's how to reclaim a VSCSI disk and its associated SAN LUN. Ordinarily, there should be no need for a reboot, either of the AIX logical partition or the Virtual I/O Server. I'm giving a sort-of high level view, skipping the SAN allocation details. Switching into reverse Removing a VSCSI disk (and its LUN) is just the... [More]

A client writes: Every time I run cfgmgr I get the following error message: Method error (/usr/lib/methods/cfgefscsi -l fscsi1 ): 0514-061 Cannot find a child device. Method error (/usr/lib/methods/cfgefscsi -l fscsi3 ): 0514-061 Cannot find a child device. SHORT ANSWER The fibre channel adapter ports reporting errors are not cabled up to the SAN switch. Nothing to worry about. Enjoy your day. Skip down to the free Coffee Time Quiz at the end of this post if you've got nothing else * to do . LONG ANSWER (verbose mode is... [More]

The Hardware Management Console, like the VIO server, is meant to be used with a restricted shell. Unlike the VIOS, though, the HMC doesn't have an easy way (* see below) of getting to its full-blown Linux shell where you can really do some damage. Problem is that if your HMC Critical Console Backup fails, it may be because the HMC's file systems are out of space, and you really need to do something about it. You may get an error such as HSCP0198 Which means it's HMC cleanup time. Waldemar Mark Duszyk has a good post explaining how to clean up... [More]

JUDGING A DISK BY ITS COVER When you have an hdisk and are wonderig what it might be used for, you can use the readvgda command. This displays all sorts of helpful infomation about the Volume Group Descriptor Area (VGDA) which is on every hdisk that belongs to a volume group. It's the sort of information you'd expect to get from the LVM commands such as lslv and lspv , with this difference: the volume group doesn't need to be varied on for you to inspect its VGDA. You can even run readvgda on the VIO server to see what logical volumes are... [More]

When you place a support call with IBM, you're usually likely to be asked to run the snap command. If there was a core dump, you may also be asked to run the snapcore command. We're going to look at them both now. snap to it The snap command, according to the snap command documentation , "gathers system configuration information and compresses the information into a pax file. " I have heard that it originated with an IBMer who got fed up with asking 20 questions every time a support call came across the desk. When you run snap,... [More]

FROM root TO padmin: THERAPY FOR AIXers When you log in to the VIO server as padmin, you are running the VIO server restricted shell. If you're a diehard AIX sysadmin who is frustrated by the VIOS command line, it can be difficult. Even a simple command like this: lsdev -Ccdisk Gives you a Usage message like this: Option flag is not valid. # dang! Usage: lsdev [-type DeviceType ...] [-virtual] [-state DeviceState] [-field FieldName ...] [-fmt delimiter] lsdev {-dev DeviceName | -plc PhysicalLocationCode} [-child] [-field FieldName ...]... [More]

"Nothing has changed, but suddenly a service has stopped working." My colleague assured me that no changes had been made on AIX. I had good reason to believe him, as he was a cautious, experienced sys admin, and was in the middle of a change freeze anyway in the leadup to Christmas. In Australia, it is common for companies to have skeleton staff and many people taking their summer holidays, so many companies keep any configuration changes to a minimum. For retail businesses which may have increased sales around the end of December,... [More]

At the IBM Power Systems Technical University in October, there was a fascinating session on Disk IO Tuning in AIX 6.1. I didn't get to see the session, but the presentation slides are well worth reading. (URL to the slides updated, Jan 24, 2017). Even if you're not running 6.1, the principles and examples will be relevant. The session had Dan Braden as its author and was presented by Steve Nasypany, and it covered topics such as: The importance of I/O tuning Disk basics and performance overview How to improve disk... [More]